1. Field of the Invention
This invention relates to a lathe, more particularly to a lathe machine for processing a bore in a workpiece.
2. Description of the Related Art
A computer-numerical-controlled lathe, or commonly called CNC lathe, generally includes a headstock, a turret, and a tailstock. The headstock is used for clamping fixedly a workpiece. The turret has a rotatable turret disk. A plurality of cutters are mounted on the turret disk so that a user can select the type of cutter needed for a cutting operation of a workpiece. The tailstock is used only when the workpiece is long, and is used to abut against the workpiece, so that a stable cutting operation of the workpiece can be achieved.
When the lathe machine has to perform a boring process of the workpiece, a boring cutter is mounted on the turret disk. Since the boring cutter is mounted fixedly on the turret disk, to prevent inaccuracy caused by vibration of the cutter, a suspended length of the cutter should not be long. Hence, the length of the cutter extending out of the turret disk is limited. As a result, the boring of the workpiece cannot be made deep. If the cutter is bored deeply into the workpiece, the workpiece is likely to bump onto the turret disk.